Anti-ultraviolet biocidal composition

ABSTRACT

A biocidal formulation with improved resistance to ultraviolet rays comprising: (a) an appropriate biocide which is Bacillus thuringiensis; (b) an anti-ultraviolet agent selected from the group consisting of 2-(2-H-benzotriazole-2-yl)-phenol and their derivatives represented by the following formula: ##STR1## wherein R 1  and R 2  are independently selected from the group consisting of alkyl, aryl, and alkylaryl groups; (c) pre-gelatinized starch; and (d) natural starch, the biocide, the anti-ultraviolet agent, the pre-gelatinized starch and the natural starch are mixed then baked at 60°-90° C. to form the biocidal formulation.

FIELD OF THE INVENTION

This invention relates to a biocidal formulation with improvedresistance against degradation upon exposure to ultraviolet rays. Moreparticularly, this invention relates to a biocidal formulation whichcomprises at least one biocide, at least one anti*ultraviolet agent,and, optionally, starch.

BACKGROUND OF THIS INVENTION

The conventional way in the prevention of agricultural pests alwaysinvolves the use of large amounts of chemical pesticides. However, longterm usage of chemical pesticides may cause pests to attain resistanceto the pesticides. Large dosages of pesticides also cause the problemsof residuals of pesticides which could cause pesticidal pollution to theenvironment. Since chemical pesticides are potentially dangerous tohuman beings and the environment, the amounts of chemical pesticidesshould preferably be reduced whenever practicable and their applicationslimited. It is also preferred that the biocides to be used caneffectively and selectively kill pests and which can be degraded in theenvironment. The quantity and types of biocides should be judiciouslyselected so that they will not harm human beings or crops.

One of the disadvantages of biocides is that most biocides cannot resisthigh temperatures. Preparations of biocidal formulation at hightemperature may destroy biocides or reduce the activity thereof.Therefore, conventionally, the preparation of biocidal formulation mustbe processed at low temperature in order to protect biocides andmaintain their activities.

R. L. Dunkle et at discloses a method for the preparation ofstarch-encapsulated Bacillus thuringiensis in Environment Entomology(vol. 17, 120-126, 1988). This reference teaches the preparation ofstarch-encapsulated biocide as follows. Refined corn oil (2 g) was mixedwith pre-gelatinized starch powder (25 g), Chilled distilled water (60ml, 2° C.) containing a suspension of Bacillus thuringiensis spores andcrystals at a desired concentration was stirred into the starch-oilmixture to form a gelatinous mass. The mixture was allowed to stand for30 minutes at room temperature to produce a rubbery but non-sticky masswhich was processed in a blender with the addition of 25 g of starchpowder to produce small particles. After being air dried for 24 hours atroom temperature, the particles were sieved into various mesh sizes.This process was applied in order to avoid the reduction of the activityof biocide due to heat or high temperature. However, this process iscumbersome and cannot be performed as a continuous process.

Another disadvantage of the conventional biocides is that most biocidescan be easily destroyed upon exposure to sunlight. The ultraviolet raysof the sunlight is specifically harmful to biocides. Thus biocides mustbe applied frequently and in large quantities in order to supplement theloss due to degradation and thus to effectively kill pests. Since largeamounts of biocides, i.e., much larger than the optimum required ofbiocides, are required to achieve the desired biocidal activity, theconventional method for the application of biocides is not economical;it also can cause health and environmental concerns.

Several researchers have studied the use of anti-ultraviolet agent inorder to protect biocides against ultraviolet degradation. R. L. Dunkleet al. discloses the application of 4-aminoazobenzene as ananti-ultraviolet agent in Environmental Entomology (Vol. 17, 120-126,1988). With their formulation, after the biocide is exposed toultraviolet rays for 24 hours, the mortality of pests is only 13-63% onthe seventh day. In U.S. Pat. No. 3,541,203, M. V. Ogle et al. disclosea method which employs carbon black and metal powder as a protectiveagent in the biocidal formulation. The mortality of pests reaches themaximum on the fifth day. However, in their tests, they did not exposetheir biocidal formulation to ultraviolet ray; therefore, it cannot besaid that their protective agents are effective as anti-ultravioletagent. In U.S. Pat. No. 4,918,586, H. A. Bohm et al. disclose a methodwhich employs benzophenone, para-aminobenzoic acid, benzyl, methylorange, methyl green, malachite green, brilliant green, methyl blue, FDCgreen, FDC red and acridine yellow as anti-ultraviolet agents. However,with their formulations, the mortality of pest was tested to be in therange of 30.7% and 71.43%.

SUMMARY OF THE PRESENT INVENTION

Having discussed the importance and desirability for a biocidalcomposition to possess ultraviolet resistance, and the inadequacy ofprior art biocidal formulations to provide such capability, the primaryobject of the present invention is, therefore, to develop a biocidalformulation which provides excellent biocidal activity even afterexposure to ultraviolet light.

This invention relates to the preparation of a biocidal formulationwhich contains at least one biocide, at least one anti-ultravioletagent, starch and water. The ingredients of the biocidal formulation areprocessed at 60°-90° C., dried for 2-15 minutes and crushed.

The present invention discloses a biocidal formulation which comprisesat least one biocide and at least one anti-ultraviolet agent. Thebiocidal formulation of the present invention may optionally containstarch. After many years of dedicated research, the co-inventors of thepresent invention found that titanium dioxide and the derivatives of2-(2-H-benzotriazole-2-yl) phenol can serve as excellentanti-ultraviolet agents, which, when added to a biocidal formulation,can effectively protect biocide against degradation upon exposure toultraviolet light.

The derivatives of 2-(2-H-benzotriazole-2-yl) phenol disclosed in thepresent invention are represented by the following formula: ##STR2##wherein R₁ and R₂ are independently selected from the group consistingof alkyl, aryl, and alkylaryl groups.

Preferred species of the derivatives of 2-(2-H-benzotriazole-2-yl)phenol include the following compounds represented by the followingformulas: ##STR3##

DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention will now be described more specifically withreference to the following examples. It is to be noted that thefollowing descriptions of examples including preferred embodiments ofthis invention are presented herein for purpose of illustration anddescription; it is not intended to be exhaustive or to limit theinvention to the precise form disclosed.

Preparation of the Bacillus thuringiensis Culture

Bacillus thuringiensis was added into a 500 ml Hinton flask whichcontained 75 ml of an appropriate culture medium. The flask was stirredat 200 rpm and 30° C. for 72 hours. After the culture preparation, theflask was sampled and found to contain 2-3×10⁻³ spores/ml. The sporeswere freezed to dry.

EXAMPLE 1

Pre-gelatinized starch (16.25 g), natural starch (81.3 g), Bacillusthuringiensis (1.0 g), and water (53.6 g) were blended to form ahomogeneous mass. The mass was dried at room temperature and crushedinto flakes. The flakes were sieved and various sizes of the flakescontaining the biocidal formulation were obtained which were exposed to310 nm ultraviolet rays for 24 hours. The results of mortality testsconducted on 3-instar moth larva are shown in Table 1.

Table 1 shows that the size of biocidal formulation influenced theanti-ultraviolet ability of the formulation. When the size of theformulation was small, the anti-ultraviolet ability was inefficient. R.L. Dunkle used larger flake size of his biocidal formulation to protectbiocides.

                  TABLE 1                                                         ______________________________________                                                         number              Mortality                                        Exposed  of moth   number of moth                                                                          of                                       Flake Size                                                                            to UV    larva tested                                                                            larva died                                                                              moth larva                               ______________________________________                                        >10 mesh                                                                              No       130       130       100                                              Yes      130        80        62                                      10-25 mesh                                                                            No       130       130       100                                              Yes      130        59        45                                      25-40 mesh                                                                            No       130       130       100                                              Yes      130        26        20                                      <40 mesh                                                                              No       130       130       100                                              Yes      130        17        12                                      ______________________________________                                    

EXAMPLE 2

Pre-gelatinized starch (312 g), natural starch (1650 g), Bacillusthuringiensis (19.2 g), and water (1030 g) were blended to form a mass.The mass was separated to equal portions. Each portion of the mass had150 g of dried weight which was equivalent to 232 g of wet weight.Various anti-ultraviolet agents (at 6 g and 18 g, respectively) wereblended with each portion of the mass, respectively. The mixture wasrolled and pressed by a hot roller at 60°-90° C. for 2.5-5 minutes. Thenthe product was crushed to obtain various sizes of biocidal formulationsin the form of flakes. After the biocidal formulation of the presentinvention was exposed to 310 nm ultraviolet rays for 24 hours, themortality of 3-instar moth larva was studied with the results shown inTables 2(a)-(d). Table 2(e) contains mortality data for the samebiocidal formulation that does not contain anti-ultraviolet agents.

EXAMPLE 3

Pre-gelatinized starch (163 g), natural starch (921 g), Bacillusthuringiensis (20 g) and water (536 g) were blended to form a mass. Themass was divided into several equal portions. Each portion of the masshad 150 g of dried weight which was equivalent to 222 g of wet weight.Various anti-ultraviolet agents at various concentrations (2 g-16 g)were blended with each portion, respectively. The mixture was rolled andpressed by a hot roller at 60°-90° C. for 2.5-5 minutes. Then theproduct was crushed into flakes of various sizes. After the biocidalformulation of the present invention was exposed to 310 nm ultravioletrays for 16 hours, the mortality of 3-instar moth larva was studied withthe results shown in Tables 3(a)-(c). Table 3(d) contains mortality datafor the same biocidal formulation that does not contain anti-ultravioletagents. Tables 3(a)-(d) show that the biocidal formulations wereeffective in protecting biocides against ultraviolet degradation even atlow concentrations of the anti-ultraviolet agents used in the presentinvention. Without the anti-ultraviolet agents, the biocides lostessentially all their activities after exposure to ultraviolet ray.

In Table 3, two various dosages of the biocidal formulations were used;they are described below:

Dosage B: 0.06 g of the biocidal formulation prepared above was exposedto 310 nm UV (0.85 mW/cm² strength) for 16 hours. The biocidalformulation was dispersed in 10 ml water. Then 2 ml of the aqueoussolution was sprayed on both sides of cabbage leaves to test themortality of moth larva.

Dosage A: 0.1 g of the biocidal formulation prepared above was exposedto 310 nm UV for 16 hours. The biocidal formulation was dispersed in 10ml water. Then 2 ml of the aqueous solution was sprayed on both sides ofcabbage leaves to test the mortality of mortality of moth larva.

The foregoing description of the preferred embodiments of this inventionhas been presented for purposes of illustration and description. Obviousmodifications or variations are possible in light of the above teaching.The embodiments were chosen and described to provide the bestillustration of the principles of this invention and its practicalapplication to thereby enable those skilled in the art to utilize theinvention in various embodiments and with various modifications as aresuited to the particular use contemplated. All such modifications andvariations are within the scope of the present invention as determinedby the appended claims when interpreted in accordance with the breadthto which they are fairly, legally, and equitably entitled.

                                      TABLE 2(a)                                  __________________________________________________________________________                             Exposed to                                                                          mortality of moth larva                        Anti-ultraviolet agent                                                                   Concentration                                                                         Size  UV ray                                                                              1 day                                                                             2 days                                                                            3 days                                 __________________________________________________________________________    TiO.sub.2  3.85%   25-40 mesh                                                                          No    20   98 100                                                             Yes   0   100 100                                                       <40 mesh                                                                            No    30  100 100                                                             Yes   2    82 100                                               10.7%   25-40 mesh                                                                          No    6    96 100                                                             Yes   12  100 100                                                       <40 mesh                                                                            No    6   100 100                                                             Yes   0   100 100                                    __________________________________________________________________________     PG,11

                                      TABLE 2(b)                                  __________________________________________________________________________                                      Exposed to                                                                          mortality of moth larva               Anti-ultraviolet agent                                                                            Concentration                                                                         Size  UV ray                                                                              1 day                                                                             2 days                                                                            3 days                        __________________________________________________________________________     ##STR4##           3.85% 10.7%                                                                           25-40 mesh <40 mesh 25-40 mesh <40                                                  No Yes No Yes No Yes No Yes                                                          8 4 10 50 22 60 28                                                               98 88 98 98 84 96 94                                                              100 96  100 100 100 98        __________________________________________________________________________                                                    100                       

                                      TABLE 2(c)                                  __________________________________________________________________________                                    Exposed to                                                                          mortality of moth larva                 Anti-ultraviolet agent                                                                          Concentration                                                                         Size  UV ray                                                                              1 day                                                                             2 days                                                                            3 days                          __________________________________________________________________________     ##STR5##         3.85% 10.7%                                                                           25-40 mesh <40 mesh 25-40 mesh <40                                                  No Yes No Yes No Yes No Yes                                                         56 18 52 34 64 32 50 22                                                            98 80 100 96 100 84 94                                                           100 98 100 100 100 100 100                                                    100                             __________________________________________________________________________

                                      TABLE 2(d)                                  __________________________________________________________________________                                  Exposed to                                                                          mortality of moth larva                   Anti-ultraviolet agent                                                                        Concentration                                                                         Size  UV ray                                                                              1 day                                                                             2 days                                                                            3 days                            __________________________________________________________________________     ##STR6##       3.85% 10.7%                                                                           25-40 mesh <40 mesh 25-40 mesh <40                                                  No Yes No Yes No Yes No Yes                                                         20 0 10 0 18 2 12 2                                                               100 50 100 28 100 80 100 64                                                       100 78 100 52 100 96 100          __________________________________________________________________________                                                86                            

                  TABLE 2(e)                                                      ______________________________________                                        Comparative Experiment*                                                       Anti-ultraviolet                                                              agent      Exposed to UV ray                                                                           Mortality after 3 days                               ______________________________________                                        None       No            100                                                             Yes           0                                                    ______________________________________                                    

                                      TABLE 3(a)                                  __________________________________________________________________________                             Exposed to                                                                          mortality of moth larva                        Anti-ultraviolet agent                                                                   Concentration                                                                         Size  UV ray                                                                              Dosage B                                                                            Dosage A                                 __________________________________________________________________________    TiO.sub.2  1.32%   25-40 mesh                                                                          No    97                                                                      Yes   93                                                                <40 mesh                                                                            No    94                                                                      Yes   77                                                        2.60%   25-40 mesh                                                                          No    98                                                                      Yes   99                                                                <40 mesh                                                                            No    92                                                                      Yes   89                                                        3.85%   25-40 mesh                                                                          No    99                                                                      Yes   96                                                                <40 mesh                                                                            No    98                                                                      Yes   91                                             __________________________________________________________________________

                                      TABLE 3(b)                                  __________________________________________________________________________                                      Exposed to                                                                          mortality of moth larva               Anti-ultraviolet agent                                                                            Concentration                                                                         Size  UV ray                                                                              Dosage B                                                                            Dosage A                        __________________________________________________________________________     ##STR7##           1.32% 2.60% 3.85%                                                                     25-40 mesh <40 mesh 25-40 mesh <40 mesh 25-40                                 mesh <40 mesh                                                                       No Yes No Yes No Yes No Yes No Yes No                                         Yes    97 36 95 20 100 72 99 44 97 77                                               96 69 100 97 97 68 100 100 98 77                                                    95 88 100 97                    __________________________________________________________________________

                                      TABLE 3(c)                                  __________________________________________________________________________                                      Exposed to                                                                          mortality of moth larva               Anti-ultraviolet agent                                                                          Concentration                                                                         Size    UV ray                                                                              Dosage B                                                                            Dosage A                        __________________________________________________________________________     ##STR8##         1.32% 2.60% 3.85%                                                                     25-40 mesh <40 mesh 25-40 mesh <40 mesh 25-40                                 mesh <40 mesh                                                                         No Yes No Yes No Yes No Yes No Yes No                                         Yes    98 82 100 62 94 64 92 100 98 80                                              100 62                                                                              100 86 100 64 100 95 46 76                                                    100 96 100 75                   __________________________________________________________________________

                  TABLE 3(d)                                                      ______________________________________                                        Comparative Experiment                                                                Exposed to                                                                              mortality of moth larva                                     Size      UV ray      Dosage B  Dosage A                                      ______________________________________                                        <40 mesh  No          90        99                                                      Yes         10        10                                            ______________________________________                                    

What is claimed is:
 1. A biocidal formulation with resistance toultraviolet rays comprising:(a) Bacillus thuringiensis; (b) ananti-ultraviolet agent selected flora the group consisting of2-(2-H-benzotriazole-2-yl)-phenol and derivatives thereof represented bythe formula: ##STR9## wherein R₁ and R₂ are independently selected fromthe group consisting of alkyl, aryl, and alkylaryl groups; (c)pre-gelatinized starch; and (d) natural starch; wherein said biocide,said anti-ultraviolet agent, said pre-gelatinized starch and saidnatural starch are mixed then baked at 60°-90° C. to form said biocidalformulation.
 2. The biocidal formulation in accordance with claim 1wherein said anti-ultraviolet agent is a2-(2-H-benzotriazole-2-yl)-phenol derivative represented by the formula:##STR10##
 3. The biocidal formulation in accordance with claim 1 whereinsaid anti-ultraviolet agent is a 2-(2-H-benzotriazo-2-yl)-phenolderivative represented by the formula: ##STR11##
 4. The biocidalformulation in accordance with claim 1 wherein said anti-ultravioletagent is a 2-(2H-benzotriazo-2-yl)-phenol derivative represented by theformula: ##STR12##
 5. The biocidal formulation in accordance with claim1 wherein said anti-ultraviolet agent constitutes 1-15% based on driedweight of said biocidal formulation.
 6. The biocidal formulation inaccordance with claim 5 wherein said anti-ultraviolet agent constitutes1-10% based on dried weight of said biocidal formulation.